Inlet cowl for a turbine engine

ABSTRACT

The disclosure is towards an inlet cowl for a turbine engine including a surface defining an inlet with a flow path and a method towards controlling the airflow in the flow path. The inlet cowl further includes an inlet lip and inner and outer barrels. The inlet lip confronts the inner barrel at a junction defining a gap.

BACKGROUND OF THE INVENTION

Contemporary aircraft turbine engines used in commercial aircraft areconventionally of a fan jet construction, e.g., the engines have a highvolume fan at an axially forward end for forcing air into a first flowpassage through an axial compressor, combustor and turbine and into asecond bypass flow passage for providing thrust. The fan is positionedwithin a nacelle surrounding and spaced from a core engine housingcontaining the compressor, combustor and turbine, the space between thenacelle structure and core engine housing defining the bypass flowpassage. During static operation of the engine, a crosswind can generatea distorted inlet airflow resulting in undesirable conditions near thefan blades. If not corrected this distorted inlet airflow can affect theefficiency of the compressor and fan blade aeromechanics.

BRIEF DESCRIPTION OF THE INVENTION

In one aspect, an inlet cowl for a turbine engine comprising an annularbody with a surface defining an inlet opening and an outlet opening todefine a flow direction from the inlet opening to the outlet opening,with the surface having a cross-sectional profile with a protuberance inthe surface of the inlet opening.

A turbine engine comprising an inlet and an exhaust, with a compressorsection, a combustion section, and turbine section in axial arrangementto define a flow path between the inlet and the exhaust, an annularinlet cowl having an inlet lip with a surface, an inner barrel, and anouter barrel, the surface confronting the inner barrel at a junction,and a protuberance at the junction.

A method of controlling airflow distortion in an inlet cowl of a turbineengine comprising an annular body with a surface defining an inletopening and an outlet opening to define a flow direction from the inletopening to the outlet opening, the method comprising reducing airflowseparation along an interior surface of the inlet by flowing air over aprotuberance on the surface of the inlet cowl.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a schematic view of an aircraft engine assembly illustratingan engine core surrounded by a nacelle, with a portion of an annularinlet cowl of the outer nacelle cut away for clarity.

FIG. 2 is an enlarged view of a portion of the annular inlet cowlshowing an inlet lip and inner/outer barrels from FIG. 1.

FIG. 3 is a schematic cross-section of a junction of an inlet lip andinner barrel of FIG. 2.

FIG. 4 is a perspective view of the annular inlet cowl.

FIG. 5 is a second embodiment of a junction of the annular inlet cowl ofFIG. 2.

FIG. 6 is a third embodiment of a junction of the annular inlet cowl ofFIG. 2.

FIG. 7 is a fourth embodiment of a junction of the annular inlet cowl ofFIG. 2.

FIG. 8 is a fifth embodiment of a junction of the annular inlet cowl ofFIG. 2.

FIG. 9A is a schematic illustration of the annular inlet cowl with anairflow.

FIG. 9B is a schematic illustration of the annular inlet cowl with anairflow and including a protuberance.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Embodiments of the present disclosure described herein are directed to aprotuberance provided on a surface of an annular inlet cowl at ajunction between an inlet lip and an inner barrel. For purposes ofillustration, the present invention will be described with respect to ageneric turbofan jet engine. It will be understood, however, that theinvention is not so limited and may have general applicability within anengine, including compressors, as well as in non-aircraft applications,such as other mobile applications and non-mobile industrial, commercial,and residential applications.

As used herein, the term “forward” or “upstream” refers to moving in adirection toward the engine inlet, or a component being relativelycloser to the engine inlet as compared to another component. The term“aft” or “downstream” used in conjunction with “forward” or “upstream”refers to a direction toward the rear or outlet of the engine or beingrelatively closer to the engine outlet as compared to another component.

Additionally, as used herein, the terms “radial” or “radially” refer toa dimension extending between a center longitudinal axis of the engineand an outer engine circumference.

All directional references (e.g., radial, axial, proximal, distal,upper, lower, upward, downward, left, right, lateral, front, back, top,bottom, above, below, vertical, horizontal, clockwise, counterclockwise,upstream, downstream, forward, aft, etc.) are only used foridentification purposes to aid the reader's understanding of the presentinvention, and do not create limitations, particularly as to theposition, orientation, or use of the invention. Connection references(e.g., attached, coupled, connected, and joined) are to be construedbroadly and can include intermediate members between a collection ofelements and relative movement between elements unless otherwiseindicated. As such, connection references do not necessarily infer thattwo elements are directly connected and in fixed relation to oneanother. The exemplary drawings are for purposes of illustration onlyand the dimensions, positions, order and relative sizes reflected in thedrawings attached hereto can vary.

FIG. 1 illustrates an aircraft engine assembly 10 having a centerline CLand including a turbine engine 12, a fan assembly 14, and a nacelle 16.The turbine engine 12 includes an engine core 18 having a compressor 20,a combustor 22, a turbine 24, and an exhaust 26 section. An inner cowl32 radially surrounds the engine core 18.

The compressor 20, combustor 22, and turbine 24 drive the fan assembly14 including fan blades 28, and a spinner 30. While only two blades 28are shown, it should be appreciated that a plurality of blades 28typically circumscribe the spinner 30. The fan assembly 14 can furtherinclude an annular forward casing 33 and an aft casing 34 forming aportion of an outer cowl 36 formed by the nacelle 16.

The nacelle 16 further includes an annular inlet cowl 38 with a body 39having a surface 88 defining an inlet opening 40 and an outlet opening41. An inlet airflow 42 runs from the inlet opening 40 to the outletopening 41. A portion 44 of the inlet airflow 42 passes into the engine10 where it is compressed, mixed with fuel and ignited in the combustor22. A larger portion 46 of the inlet airflow 42 bypasses the engine core18 through a bypass duct 48.

The annular inlet cowl 38 includes radially spaced inner and outerbarrels 50, 52 that abut an annular nose lip section 54 provided axiallyupstream of the barrels 50, 52. The annular nose lip section 54terminates in an inlet lip 56 and an outer lip 58. The outer lip 58 canbe connected to the outer barrel 52 by circumferentially spacedfasteners 60, such as rivets or the like. By way of a non-limitingexample, the inlet lip 56 and the inner barrel 50 define the surface 88.It can be further contemplated that the surface 88 can be defined by anyportion of the annular inlet cowl 38 including the outer barrel 52 andouter lip 58.

Turning to FIG. 2, an enlarged view of the nose lip section 54illustrates a junction 80 between the inlet lip 56 and the inner barrel50. A forward bulkhead 62 extends between radially spaced apart upstreamedges 64, 66 of the inner and outer barrels 50, 52. An aft bulkhead 68connects radially spaced apart inner and outer barrel aft ends 70, 72 ofthe inner and outer barrels 50, 52. The forward and aft bulkheads 62, 68contribute to the rigidity and strength of the annular inlet cowl 38.The inlet lip 56 terminates in a downstream edge 74 where it confrontsthe upstream edge 64 of the inner barrel 50.

FIG. 3 depicts an enlarged view of a cross-section of a first embodimentof the junction 80 defining an intervening gap 82 between the downstreamedge 74 of the inlet lip 56 and the upstream edge 64 of the inner barrel50. A protuberance 84 extends radially inward from an outer surface 86of the barrel 50 with a maximum height H. The maximum height H can varyon several factors, including the size of the inlet and the expectedoperating conditions. For a subsonic inlet flow of a turbine engine forcontemporary commercial aircraft, a maximum height H is one to two timesthe displacement thickness δ* calculated:δ*=∫0δ(1−^(u)/_(U))dywhere u is the velocity at a distance y from the surface 88, U is thevelocity of airflow 42, and δ is a boundary layer thickness: a distancemeasured from the surface to a point where u/U=0.99. The boundary layerδ and displacement thickness δ* on the inlet surface 88 can be measuredusing pressure sensing elements embedded into the flow near the surface88 across an applicable range of corrected fan speeds, N1K.Alternatively, accurate numerical calculations can be done to achievethe same. Once the displacement thickness δ* is established for thepart-speed fan region where flow separation occurs, then maximum heightH of the protuberance is established and used during the operation ofthe inlet, without having to measure it again.

The maximum height H is measured perpendicularly from the surface 88 atthe inlet lip 56. The protuberance 84 is chamfered terminating in a tip90 at the upstream edge 64 of the barrel 50. The tip 90 can be flushwith the surface 88 at the inlet lip 56, or radially outward of or belowthe downstream edge 74 as illustrated.

Turning to FIG. 4, a perspective view of the annular inlet cowl 38 showsthe protuberance 84 within the annular inlet cowl 38 spanning at least180 degrees of the inner barrel 50. The at least 180 degrees of theprotuberance 84 is provided along a portion 92 of the annular inlet cowl38 confronting a crosswind 94. While illustrated as 180 degrees, it iscontemplated that the protuberance 84 can be more or less than 180degrees, including a full 360 degrees within the entirety of the innerbarrel 50.

Under normal operating conditions, air enters the annular inlet cowl 38as a normal inlet airflow 42. The presence of a crosswind 94 cangenerate a distorted inlet airflow 96 in which the normal inlet airflow42 separates, decreasing the pressure in the annular inlet cowl 38resulting in a distorted inlet airflow 96 reaching the fan blades 28.This distorted inlet airflow 96 increases the inefficiency of thecompressor, including the possibility of a compressor stall. Introducingthe protuberance 84 to the annular inlet cowl 38 decreases the amount ofseparation in the airflow 42 enabling the engine to operate within anoperational envelope dictated by the maximum level of crosswind theaircraft can handle. By minimizing or preventing an airflow separation,the operational envelope can be expanded. For example, in an aircraftthat can sustain a maximum level of crosswind of 25 knots, introducingthe protuberance 84 could increase the envelope to include crosswinds ofup to 30 knots.

Turning to FIGS. 5, 6, and 7 alternative embodiments of the protuberanceare illustrated with like parts identified by like numerals increasingby 100, with it being understood that the description of the like partsof the various aspects described herein applies to the additionalembodiments, unless otherwise noted.

An alternative embodiment of a protuberance 184 is depicted in FIG. 5,where the protuberance 184 is rounded with a longer axial face 198 thanthe chamfered protuberance 84 of FIG. 4.

A third embodiment illustrated in FIG. 6 is a protuberance 284comprising a movable element 285 wherein the movable element 285 iscoupled to a pivot mount 251 within the inner barrel 250 at an inner end265. An upstream edge 264 of the movable element 285 can be one of achamfered or rounded edge. In a first position 276, a surface 288 at themovable element 285 is flush with the surface 288 at an inlet lip 256.In a second position 278, the inner end 265 of the movable elementremains stationary while the upstream edge 264 is provided at a maximumheight H radially outward of the surface 288. The maximum height H canvary on several factors, including the size of the inlet and theexpected operating conditions. As described herein, a maximum height Hcan be one to two times the displacement thickness δ*.

An actuator 200 is provided below the movable element 285 at theprotuberance 284 in a position radially outward the inner barrel 250.The actuator 200 can be a thermal actuator, for example but not limitedto a wax motor including a thermally reactive element 201 that willexpand when heated. The thermal actuator is not meant to be limiting andit should be understood that any mechanical element known in the art canalso be provided to actuate the moveable element.

Turning to FIG. 7, a fourth embodiment of a protuberance 384 comprisingan annular strip 379 is illustrated. In a first position 376 the annularstrip 379 is ensconced downstream of an upstream edge 364 of an innerbarrel 350 in a channel 383 provided in the inner barrel 350. In asecond position 378, the annular strip 379 is radially inward of thechannel 383 at a maximum height H above a surface 388 of the inlet lip356. The maximum height H can vary on several factors, including thesize of the inlet and the expected operating conditions. As describedherein, a maximum height H can be one to two times the displacementthickness δ*. A thermal or mechanical actuator 300 as described hereinis provided below the annular strip 379 to move it from the firstposition 376 to the second position 378. The annular strip can be anymaterial capable of expanding and contracting when moved the maximumheight H and able to sustain large temperature differentials, by way ofnon-limiting example silicone.

FIG. 8 is a fifth embodiment in which a protuberance 484 is contemplatedas downstream from a channel 483 formed at the junction 480. The channelhas a depth of H, and as described herein, a maximum H can be one to twotimes the displacement thickness δ*. The channel 483 is provided in asurface 488 upstream of the protuberance 484. The channel 483 can beformed in the inner barrel 450 and the inlet lip 456 as illustrated. Itcan also be contemplated that the channel 483 is formed in one of theinner barrel 450 or the inlet lip 456.

The protuberance can be any shape including but not limited to sharp orrounded, ramped or fined, sphere or rectangular. The protuberance cancomprise for example but not limited to a collection of deformations,walls, fins, or the like to define a surface roughness. The embodimentsdisclosed herein are exemplary and not meant to be limiting.

FIG. 9A is a schematic illustration of an annular inlet cowl without theprotuberance 84 illustrating airflow separation that can occur along asurface 88.

FIG. 9B is a schematic illustration of the annular inlet cowl 38described herein with a protuberance 84. A method for controllingairflow distortion 96 in the annular inlet cowl 38 includes reducingairflow separation 97 along an interior surface 89 of the inlet cowl 38by flowing air over the protuberance 84 downstream of the inlet opening40. The interior surface 89 is a region anywhere along the surface 88 inthe interior of the inlet opening 40 up to the fan blades 28. Theprotuberance 84 is formed along the portion 92 of the turbine engineconfronting the crosswind 94.

It is further contemplated that a fan diameter D_(fan) and lip skinlength L can be measured as illustrated in FIG. 9B to further define themaximum height H. For the protuberance 84 as described herein, a ratioof H/D_(fan) between 0.0005 and 0.004 for a subsonic inlet with aL/D_(fan) ratio between 0.2 and 0.5 is also contemplated.

In the case where the protuberance 284, 384 is a movable element 285,385, the method can include actuating the protuberance 284, 384 uponreceiving a signal by moving the protuberance 284, 384 from the firstposition 276, 376 to the second position 278, 378. The signal can be oneof automation or pilot controlled.

In the case of an automatic signal, the actuator can be programmed tomove the protuberance 284, 384 from the first position 276, 376 to thesecond position 278, 378 when the fan reaches a first speed and back tothe first position 276, 376 when the fan reaches a second speed. Therange from the first speed to the second speed can be between 50 and100% N1K, a corrected speed nomenclature. Corrected speed is the speed acomponent would rotate at if the inlet temperature corresponded toambient conditions at sea level on a standard day and can be abbreviatedto N, in this case N1K, on the magnitude of 1000 rpm.

It is also contemplated that the actuator is a thermal actuator in whichcase the protuberance would be moved from the first 276, 376 to thesecond position 278, 378 and back to the first position 276, 376 underthermal conditions coinciding with fan speeds between 50 and 100% N1K.

Providing a protuberance in the surface of the inlet cowl reduces fluidseparation near the fan blades. Tests performed using the methoddescribed herein produced an expansion between 10 and 20% N1K betweenpart-speed separation and high-speed separation in the inlet cowl. Thereduction in fluid separation significantly reduces the possibility of acompressor stall, increasing operational envelopes in which jet enginesmust operate.

Commercial benefits relate to strict crosswind operational envelopesrequired for commercial jet engines as well as aircraft maneuvers due toallowable limits on flow distortion. The protuberance 84 and method tocontrol the flow separation characteristics of an inlet described hereinprovide larger flexibility in designing smaller and slimmer inlets withlower drag and lower weight and lower weight fan blades with better aerodesign. Lower weight allows for better overall performance and anintroduction of the protuberance 84 enables less restrictive crosswindoperational envelopes for the commercial airliners. A decrease in fluidseparation leads to better durability for turbomachinery and flightinlet development for high bypass ratio turbofan engines.

To the extent not already described, the different features andstructures of the various embodiments may be used in combination witheach other as desired. That one feature may not be illustrated in all ofthe embodiments is not meant to be construed that it may not be, but isdone for brevity of description. Thus, the various features of thedifferent embodiments may be mixed and matched as desired to form newembodiments, whether or not the new embodiments are expressly described.All combinations or permutations of features described herein arecovered by this disclosure.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

What is claimed is:
 1. An inlet cowl for a turbine engine comprising: anannular body defining an inlet opening and an outlet opening to definean inlet airflow flowing in a flow direction from the inlet opening tothe outlet opening, the annular body comprising: an annular nose sectionat the inlet opening terminating in a downstream edge and defining afirst portion of an inner surface of the inlet opening; and an innerbarrel defining a second portion of the inner surface and having across-sectional profile extending between an outer surface of the innerbarrel and the second portion of the inner surface to define a radialdirection with a protuberance having a tip and an axial face extendingfrom the tip to the second portion of the inner surface, theprotuberance extending radially beyond the first portion of the innersurface of the inlet opening to define a height; wherein the annularnose section is spaced from the inner barrel to define a gap and the tipis located downstream of the gap with respect to the inlet airflow. 2.The inlet cowl of claim 1 further comprising an outer barrel radiallyspaced from the inner barrel.
 3. The inlet cowl of claim 2 wherein theprotuberance is formed only on the inner barrel.
 4. The inlet cowl ofclaim 2 wherein the gap is formed between the downstream edge and anupstream edge of the inner barrel.
 5. The inlet cowl of claim 1 whereinthe protuberance faces the inlet opening.
 6. The inlet cowl of claim 1wherein the protuberance is chamfered or rounded.
 7. The inlet cowl ofclaim 4 further comprising a movable element wherein the movable elementselectively forms the protuberance.
 8. The inlet cowl of claim 7 whereinthe movable element is pivotally coupled within the inner barrel at aninner end downstream from the upstream edge of the inner barrel.
 9. Theinlet cowl of claim 8 wherein the movable element is chamfered orrounded.
 10. The inlet cowl of claim 9 further comprising an actuatoroperably coupled to the movable element to move the movable element inorder to adjust the height.
 11. The inlet cowl of claim 10 wherein theactuator is at least one of a thermal or mechanical element.
 12. Theinlet cowl of claim 1 wherein the protuberance is disposed on a side ofthe inlet cowl confronting a crosswind.
 13. The inlet cowl of claim 1wherein the height is a function of a boundary layer thickness or a fandiameter.
 14. A turbine engine comprising: an inlet and an exhaust, witha compressor section, a combustion section, and a turbine section inaxial arrangement to define a flow path between the inlet and theexhaust; an annular inlet cowl having an inlet lip defining a firstportion of an inner surface of the inlet and terminating in a downstreamedge, an inner barrel defining a second portion of the inner surface ofthe inlet, and an outer barrel, the downstream edge confronting theinner barrel; a junction defining an intervening gap between thedownstream edge of the inlet lip and an upstream edge of the innerbarrel; and a protuberance having a tip located downstream of theintervening gap with respect to the flow path, the protuberance definingat least a portion of the upstream edge continuing from the secondportion of the inner surface of the inlet, located in the inner barrelat the junction, confronting the flow path, and extending radiallybeyond the inner surface.
 15. The turbine engine of claim 14 wherein theprotuberance faces the inlet.
 16. The turbine engine of claim 14 whereinthe protuberance is chamfered or rounded.
 17. The turbine engine ofclaim 14 further comprising a movable element wherein the movableelement selectively forms the protuberance.
 18. The turbine engine ofclaim 17 wherein the movable element is pivotally coupled within theinner barrel at a location downstream of the upstream edge of the innerbarrel.
 19. The turbine engine of claim 18 wherein the movable elementis rounded or chamfered.
 20. The turbine engine of claim 17 furthercomprising an actuator operably coupled to the movable element in orderto adjust a height of the protuberance.
 21. The turbine engine of claim20 wherein the actuator is at least one of a thermal or mechanicalelement.
 22. The turbine engine of claim 14 wherein the protuberance isdisposed on a side of the turbine engine confronting a crosswind. 23.The turbine engine of claim 14 wherein the protuberance has a maximumheight that is a function of a boundary layer thickness or a fandiameter.
 24. A method of controlling airflow distortion the turbineengine according to claim 14, the method comprising: reducing airflowseparation along the inner surface of the inlet by flowing air over theprotuberance.
 25. The method of claim 24 wherein the controlling airflowdistortion further comprises actuating the protuberance.
 26. The methodof claim 25 wherein the actuating includes receiving a signal at anactuator and moving the protuberance from a first position to a secondposition.
 27. The method of claim 26 wherein the protuberance is formedalong a side of the turbine engine confronting a crosswind.